PC Magazine Explains Common Graphic File Formats

[Jason Dunn]

<div class='os_post_top_link'><a href='http://www.pcmag.com/print_article/0,3048,a=118880,00.asp' target='_blank'>http://www.pcmag.com/print_article/0,3048,a=118880,00.asp</a><br /><br /></div>"You can gain more control over the quality and size of your images by picking the right format for the job. Graphics files usually contain one of two types of data: raster—colored dots (or pixels) arranged in rows, and vector—images composed of lines, polygons, and text. Raster formats are ideal for photos, and vector formats are best for logos and diagrams. Vector formats use smooth outlines to create objects, maintaining quality even when an image is enlarged or reduced.<br /><br />Generally speaking, there are three factors to weigh when considering graphics formats: the output media (print or Web), the format's specific features, and your workflow. Typically, the only Web formats worth using are those supported by most browsers: GIF, JPEG, and SWF. Large raster images are more download- and memory-friendly if they're compressed, but lossy compression schemes (such as JPEG) shrinks images by discarding data. Also, some formats support simple transparency (where designated pixels are opaque or clear), and others offer gradient (or alpha channel) transparency effects."<br /><br />One of the fundamental pieces of knowledge necessary to working with digital images is understanding what file format is appropriate for specific tasks. This PC Magazine article is a good overview for beginners - give it a read!

[suchiaruzu]

PNG all the way :)

[ctmagnus]

Vector—or metafile—formats

I thought vector files were just lines and therefore a smaller filesize than a similar raster file. They have no more (in fact, less) data than any given raster file, taking the abilty of the originating program to create metadata into play.

Whereas a bitmap/raster image would require colour and location info for every pixel along a line in a given raster file, the same line in a vector file would be defined by only the endpoints and colour (and thickness, if any) of that line. Less data required in a file means smaller filesize.

I've never heard of the term Metafile before. I'm thinking the writer of the article pulled it out of the air as the definition I found is eight years old.

[Jason Dunn]

I've never heard of the term Metafile before. I'm thinking the writer of the article pulled it out of the air as the definition I found is eight years old.

I think he's talking about WMF - Windos Metafile. It's an old format used for clipart - it's a vector file format.

[ctmagnus]

Now I remember. :) That was way back in my Windows 3.1 days.

[Suhit Gupta]

PNG all the way :)
Yeah, I agree :), even though I still end up using GIF and JPG files for my webpage. I should seriously start switching.

Suhit